Template:MediaWiki URL rules
URLs must begin with a supported URI scheme. http:// and https:// will be supported by all browsers; however, ftp://, gopher://, irc://, ircs://, mailto: and news: may require a plug-in or an external application and should normally be avoided. IPv6 host-names are currently not supported.
If URLs in citation template parameters contain certain characters, then they will not display and link correctly. Those characters need to be percent-encoded. For example, a space must be replaced by %20. To encode the URL, replace the following characters with:
| Character | space | " | ' | < | > | [ | ] | { | | | } |
|---|---|---|---|---|---|---|---|---|---|---|
| Encoding | %20 | %22 | %27 | %3C | %3E | %5B | %5D | %7B | %7C | %7D |
Single apostrophes do not need to be encoded; however, unencoded multiples will be parsed as italic or bold markup. Single curly closing braces also do not need to be encoded; however, an unencoded pair will be parsed as the double closing braces for the template transclusion.
Template documentation